Introduction
Diabetes is a public health problem of epidemic proportions. According to recent estimates, 12.3% of US adults aged 20 years and older, and 25.9% of those aged 65 years and older, have diabetes. In addition, another 37% of US adults aged 20 years or older, and 51% of those aged 65 years or older, have prediabetes. Type 2 diabetes accounts for about 90–95% of all diagnosed cases.1
Diabetes is the seventh leading cause of death in the USA. Diabetes complications include cardiovascular disease, stroke, hypertension, blindness, kidney disease, nervous system damage, limb amputations, and biochemical imbalances that can cause acute life-threatening events. Rates of cardiovascular mortality are about 1.7 times higher among adults aged 18 years or older with diagnosed diabetes than among adults without diagnosed diabetes.1
Overweight or obesity is a primary risk factor for type 2 diabetes.2 Compared with healthy weight adults, obese individuals are more than seven times more likely to develop type 2 diabetes.3 The more fatty tissue that is present in the body, the more resistant the cells become to insulin.4 Fat stored primarily in the abdomen increases the risk of type 2 diabetes greater than if the fat were stored elsewhere, such as in the hips and thighs.4 Weight gain of as little as 10 lb over 15 years can double a person's insulin resistance and increase the risk of diabetes.4 Insulin resistance may also contribute to high blood pressure, increased triglycerides and low-density lipoprotein (LDL) cholesterol, and reduced levels of high-density lipoprotein (HDL) cholesterol.5
Weight reduction is an important objective for overweight or obese individuals with type 2 diabetes.6 A moderate and sustained weight reduction of 5–7% of body weight can improve insulin sensitivity, decrease fasting glucose, and reduce the need for some diabetes medications.2 ,7–13 Healthful eating is the cornerstone management approach for blood glucose control in diabetes by controlling body weight.1 Another important goal of type 2 diabetes management is the reduction of cardiovascular disease risk factors such as high blood pressure.1
Foods such as plant-based protein sources, for example, beans, nuts, seeds, or tofu; fish and seafood; chicken and other poultry; and low-fat dairy products with a low glycemic index are typically recommended to control blood glucose in diabetes.8 However, the inclusion of eggs in a healthful diabetic diet has been controversial. In a meta-analysis by Shin et al,14 egg consumption was associated with an increased incidence of type 2 diabetes in the general population and cardiovascular morbidity among diabetes patients. In another recent meta-analysis by Djoussé et al,15 infrequent egg consumption showed no association with type 2 diabetes, but consumption of three or more eggs per week demonstrated a modest increase in the risk of type 2 diabetes. In another recent meta-analysis by Tamez et al,16 studies conducted in the USA had a strong association between egg consumption and the incidence of type 2 diabetes, while studies conducted elsewhere showed no association. As a satiating and protein-rich food, eggs seem to have potential to foster calorie and weight control, and to reduce the dietary glycemic load, offering potential advantages in type 2 diabetes. We conducted a prospective, randomized, single-blind, controlled, crossover trial to assess the effects of daily egg inclusion (ie, 2 eggs per day) in the habitual diet for a 3-month period in comparison to egg exclusion on glycemic control, anthropometric measures, and overall diet quality in adults with type 2 diabetes.